The aim of this study was to investigate the effectiveness of chemical oxidation by applying ozonation, ozonation with hydrogen peroxide and Fenton's processes for decolorization and residual COD removal of biologically pretreated baker's yeast industry (BYI) effluents. Baker's yeast industry effluents characterizing with high COD, TKN, dark color, and non-biodegradable organic pollutants. The batch tests were performed to determine the optimum operating conditions including pH, O-3, H2O2, and FeSO4 dosages, molar ratio of Fe2+/H2O2 and reaction time. It was noticed that H2O2 significantly reduced the reaction times for the same ozone dosages; however, COD and color removals were not remarkable. In the Fenton's oxidation studies, the removal efficiencies of COD and color for 30 min reaction time for three different types of BYI effluents were found about 86 and 92%, respectively. Experimental results of the presented study have clearly indicated that the Fenton's oxidation technology is capable to fate almost all parts of the organics which consist of both soluble initial and microbial inert fractions of COD for baker's yeast effluents. Effluents from the Fenton's oxidation process can satisfy effluent standards for COD and color in general.